<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>dataBind</title>
</head>
<body>
  <input id="input" type="text"/>
  <span id="span">123</span>
  <script>
    const input = document.getElementById('input')
    const span = document.getElementById('span')

    input.addEventListener('keyup', e => {
      span.innerText = input.value
    })
  </script>
</body>
</html>